The present invention relates to fixation devices, and in particular, fixating devices for insertion into bores in materials to allow the connection of another element to the material in which the fixation is disposed. In particular, the present invention relates to a fixation device for the medical field, which can be inserted into, for example, a pre-drilled bore in bone, to allow the connection to the bone of another member, for example, a prosthetic member. Alternatively, the fixation device can have sutures attached that allow the suturing of another member to the fixation device. As an example, the fixation device of the present invention may have sutures attached thereto which allow the securement of a prosthetic device or artificial member, or a natural anatomical member, for example, ligaments, to the bone.
Although the present invention has particular application in the medical field, it is not limited thereto and may find other uses, i.e., wherever it is necessary to fasten two or more members together, especially when the members are to be secured together with fixation devices located in bore holes that are blind or open to only one side, i.e., not completely drilled through.
U.S. Pat. No. 5,268,001 to Nicholson et al. relates to a bone fastener for fixing either a suture or a rivet within a pre-drilled bone hole. In the device of that reference, the bone fastener includes an expandable sleeve having an axial bore and a pin which is forcibly insertable into the axial bore. The expandable sleeve is configured to be insertable into the bore drilled in the bone and at least a portion of the pin has an outer diameter greater than the inner diameter of at least a portion of the axial bore of the sleeve. The fastener is emplaced by inserting the sleeve into a pre-drilled hole in the bone and then forcing the pin into the axial bore of the sleeve, so that the wider portion of the pin presses outwardly against and expands the narrow portion of the sleeve, causing the sleeve to forcibly contact the walls of the bone hole and fixing the pin and sleeve firmly in place within the hole. The apparatus for emplacement of the fastener includes a holder for holding the expandable sleeve in position within the pre-drilled hole in the bone and a plunger moveable in relation to the holder for forcing the pin into the bore of the sleeve so that the pin can be forced in the axial bore without imposing substantial force toward or away from the bone. The device includes a severable attachment between the holder and the expandable sleeve which is cut by a cutting edge of a cylindrical blade. The sleeve is thereby separated from the holder body and the fully expanded and fixed fastener is freed from the insertion apparatus.
The device of the Nicholson et al. reference has several drawbacks including that a force must be applied toward the bone or member in which the fastener is being inserted. This causes greater strains than necessary to the patient because the anchor must be expanded by this pushing force, which causes undue strain on the material of the member in which the fastener is being inserted. The expandable sleeve also may not provide sufficient engaging force to secure the fastener in the bore hole in the bone because it only expands and frictionally engages in the bone without actually cutting or penetrating into the bone. Additionally, the cutting edge necessary to separate the fastener sleeve from the holder body creates additional complexity.